1. Technical Field
This invention relates to information retrieval and in particular to a method and apparatus for generating a concept dictionary in respect of an information system for use in retrieving information from that system.
2. Related Art
It is often assumed in prior art electronic information access systems that a user understands something of the structure of the stored data and the methods used to access those data to be able to access relevant information efficiently. In particular, the user may be expected to know terms that appear in stored entries of potential interest and be able to choose query terms that distinguish these entries from others stored in the system. To help avoid this dependence on user knowledge, it is known to use a thesaurus or ontology to convert queries expressed in the user's favoured terms into queries that may enable the system to retrieve the most relevant entries. For example, if no entries are found in response to a query including the word pizza, an ontology might suggest use of the term Italian restaurant instead. However, to be generally applicable, such an ontology must, of necessity, be extremely broad. Experience of the Artificial Intelligence (AI) community suggests that this approach is impractical and that it may be impossible to implement a “universal” AI-based ontology containing human-level general knowledge. In addition, because a universal ontology has to be extremely broad, it tends to over-generalise queries. For example, the word car might be replaced by reasonable synonyms such as auto, automobile, or motorcar but it might also be replaced by machine, railway car, elevator car or gondola which are not relevant to the query.